A man uses his mobile phone in front of a giant advertisement promoting Samsung Electronics' new Galaxy S5 smartphone, at an art hall in central Seoul on April 15, 2014. The S5 should outsell its predecessor and defy predictions that the South Korean titan's latest model will struggle in a tough market for high-end handsets, a top executive said. -- PHOTO: REUTERS

SEOUL (Reuters) - Samsung Electronics's new Galaxy S5 smartphone should outsell its predecessor and defy predictions that the South Korean titan's latest model will struggle in a tough market for high-end handsets, a top executive said.

The world's biggest smartphone maker has slashed prices of the S5, which rolled out globally on Friday, offered a gift pack worth US$600 (S$752), and more than doubled the number of initial launching countries to 125 in a bid to sustain growth in the mobile business, which generates 70 per cent of its total profit.

A smooth launch is crucial for Samsung, which reported its second straight quarter of profit decline earlier this month as margins in the key smartphone business come under growing pressure from cheaper Chinese rivals.

"(The S5) is selling faster than the S4 so far, though it's difficult to share specific numbers as we're still at early stages," Yoon Han-kil, senior vice president of Samsung's product strategy team, told Reuters in an interview. "S5 sales should be much better than the S4."